/Fmpathname
This option tells the linker to produce a map file containing a list of segments in the order in which they appear in the corresponding .exe file or DLL. By default, the map file is given the base name of the corresponding C or C++ source file with a .MAP extension.
Specifying /Fm has the same effect as if you had specified the /MAP linker option.
If you specify /c to suppress linking, /Fm has no effect.
Global symbols in a map file usually have one or more leading underscores because the compiler adds a leading underscore to variable names. Many global symbols that appear in the map file are used internally by the compiler and the standard libraries.
Output-File (/F) Options | Compiler Options | Setting Compiler Options | Specifying the Pathname